Anolis lizards are often studied in the context of adaptive radiation in the Greater Antilles, where they have independently diversified into various habitat types termed ecomorphs. Although members of an ecomorph share similar microhabitat preferences and corresponding adaptive morphologies, species differ according to the thermal range they occupy. Three species in the Hispaniolan radiation of trunk- and ground-dwelling anoles, Anolis cybotes, A. longitibialis, and A. shrevei inhabit different thermal environments. Anolis shrevei is found in cool montane environments while A. longitibialis is found only in hot lowland forests. Anolis cybotes, a purported generalist, is found throughout the island, except at the highest elevations. Here we test three hypotheses about the mechanisms forging different thermal ranges in these closely related species. 1) The thermal preference and thermoregulatory efficiency of each species reflects the temperatures available in their respective environments. 2) Species’ thermal tolerances match the thermal range of their environments. 3) Females from colder environments delay laying eggs to increase the rate of embryonic development. Despite their different thermal environments, these three species show similar thermal preferences and body temperatures, and do not differ in thermoregulatory efficiency. Higher elevation populations, and especially Anolis shrevei, have greater cold tolerance, but the reverse is not true for heat tolerance in low elevation populations. Egg retention in cold temperatures occurs in all species except in Anolis longitibialis. We summarize these behavioral and physiological patterns in light of thermal range experienced, and how thermal adaptation may have influenced diversification in this clade.